Various workers in the prior art have provided compositions and methods for generating sterilization and disinfecting compositions, a few of which include those in the following US patents, which are herein incorporated by reference thereto. U.S. Pat. No. 2,454,254 teaches a stabilized organic peroxide composition which contains a single phase liquid mixture of an alkyl ester of phthalic acid and an organic peroxide. U.S. Pat. No. 3,520,825 provides an organic peroxide containing paste containing from 20-65% of a solid peroxide, water, and a polyethylene glycol having a molecular weight of at least about 1000. U.S. Pat. No. 3,956,396 teaches a safe diacyl peroxide solution composition consisting essentially of: a diacyl peroxide at about 10-70% by weight; and a safety solvent for the peroxide, at about 90-30% by weight. The solvent is present in such an amount to render the solution composition safe, where the solvent is selected from the group consisting of aliphatic hydrocarbons, aliphatic ketones, aliphatic esters, aliphatic ethers, aliphatic alcohols and mixtures thereof, which boils in the range of about 140-210° C. at 760 mm. Hg, and has a vapor pressure substantially the same as that of the peroxide. U.S. Pat. No. 4,151,106 provides a process for the preparation of uniform, stable diacyl peroxide compositions comprising reacting the corresponding acyl chloride with hydrogen peroxide in an alkaline aqueous medium in the presence of a desensitizing agent. U.S. Pat. No. 4,255,277 describes a storage stable peroxide paste composition comprising: benzoyl peroxide or benzoyl peroxide having one or more substituents selected from halogen, lower alkyl or lower alkoxy; and a minor proportion of water; and finely divided particulate calcium carbonate in an amount sufficient to prevent the composition from physically separating into its components. U.S. Pat. No. 4,396,527 sets forth an aqueous emulsion of organic peroxide which is obtained by incorporating a water soluble alcohol of low molecular weight into a system which comprises an organic peroxide, an emulsifier and water. U.S. Pat. No. 4,917,816 provides an organic peroxide aqueous dispersion comprising: a) from about 35 to about 70 weight percent of solid benzoyl peroxide particles, the particles having a size of about 10 microns or less; b) water; c) a compound that produces an ionic region about the peroxide particles in the dispersion, is inert as to the peroxide, and is at least water dispersible wherein the compound is selected from the group consisting of finely divided filmed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid; d) a defoamer; and e) a water soluble acidic inorganic salt which is inert as to the peroxide and which increases the viscosity of the dispersion, retains water of hydration upon dry down of the dispersion and possesses fire retardant properties. U.S. Pat. No. 5,057,479 discloses an aqueous dispersion for use in curing polyester resins and the suspension polymerization of vinyl monomers comprising a symmetrical or asymmetrical aromatic diacyl peroxide; a water-soluble alkylene glycol; a dispersion stabilizing amount of magnesium aluminum silicate and a cellulose ether; and sufficient water to form an aqueous dispersion. U.S. Pat. No. 5,110,495 teaches an improved organic peroxide dispersion comprising: a) from about 35 to about 70 weight percent of solid organic peroxide having a particle size of 10 microns or less; b) from about 65 to 30 weight percent water; c) a dispersant, the dispersant being inert as to the peroxide and at least water dispersible and producing a dispersion having a predetermined Brookfield viscosity of at least 100 centipoises; and d) a defoamer. U.S. Pat. No. 5,654,464 teaches organic peroxide compositions which contain a cyclic alpha-diketone compound to retard the rate of decomposition of the peroxide compound.
Peroxyacids, and peroxyacetic acid in particular, have been used with considerable success in cleaning and disinfecting various surfaces and implements, including medical devices such as endoscopes, and some other environmental surfaces. However, one drawback associated with the use of peroxyacetic acid and other peroxy acids in such an end use at its final use concentrations of about 0.05% to about 5% by weight is too unstable to have a useful shelf life. In practical terms, the shelf life of such solutions is limited to a few months, rather than years, due to the inherent instability of the materials. Generally, very low concentrations of the peroxyacetic species, such as those used to disinfect surfaces (i.e., 0.05% to about 5%) are too unstable for a useful commercial shelf life. Thus, it has been found necessary when desiring to employ these materials to provide a concentrated solution immediately prior to its use and diluting to the final desired concentration. One way around the shelf life problem could be to employ a solid formulation which is mixed with water shortly before needed. According to such a method as used within the context of the prior art, active precursor components include a solid form of hydrogen peroxide such as an alkali or alkaline earth percarbonate or perborate salt in combination with an acyl donor, such as either tetraacetylethylenediamine (“TAED”) or acetylsalicylic acid. The aqueous peroxyacid generation process is described by the reaction:
with the understanding that the peroxide is present a result of the reaction of the perborate or percarbonate with water, and is subsequently available to react with the acyl compound. In the foregoing equation, the radical X represents the remaining residue of the TAED or ASA molecule, such as in the case of ASA wherein it represents the ASA molecule minus the acetyl group. However, we do not consider TAED and ASA to be efficient acylating agents, in that a relatively large mass of useless carbon-containing byproducts are generated when these reactants are employed. In addition, the kinetics of the reaction are not as favorable as would be desired, viz., to quickly generate appreciable quantities of peroxyacetic acid from ASA according to the above scheme, a reaction temperature above room temperature is required.
While peroxyacetic acid is currently used to disinfect medical equipment such as endoscopes and related items, peroxypropionic acid (“PPA”) has not been developed for such purposes due at least in part to the lack of an efficient means to produce PPA at the site of use.
The precursors of the present invention have the distinct advantage that they can be used to produce novel antimicrobial formulations which contain PPA, as well as a whole host of other peroxyacids which are relatively easy to produce and which consume less weight of hydrogen peroxide during their production per mole of peroxyacid produced than the commercial precursors acetyl salicylic acid (ASA) and tetraacetylethylenediamine (TAED), which is a great advantage. Additionally, the precursors of the present invention allow for the formulation of antimicrobial compositions that have room temperature stability in their concentrated forms and can alternatively be packaged in dry powder form for reconstitution by combination with hydrogen peroxide, or a hydrogen peroxide precursor/water mixture at the site of their end use. Thus, the resulting liquid formulations can be readily delivered in liquid or even gaseous form at the site of use. The dry powder form or its concentrate may also be applied to the site of use and activated with hydrogen peroxide or water in combination with a hydrogen peroxide precursor.
Thus, in summary, the present invention provides novel water-soluble precursors useful for generating peroxy acids more efficiently than previously provided for by the prior art. When using a precursor of the present invention, there are less by-products generated for every mole of peroxyacid generated. Further, a smaller weight of the precursor provided by the present invention is required to generate a mole of peroxy acid than when using prior art materials and/or methods. The acyl precursors provided by the present invention are generally more water-soluble than ASA, relatively inexpensive to manufacture, and consume less weight of acyl precursor per mole of peroxyacid generated than the corresponding ASA. Immediate uses for the solutions provided by the use of the various embodiments of this invention include, without limitation: emergency disinfection of wounds by mixing dry powder with water; disinfection of surgical facilities and medical treatment rooms; chemical sterilization of surgical equipment and instruments, particularly endoscopes; disinfection of medical devices; disinfection of animal enclosure areas such as used by horses, cattle, dogs, cats, etc.; remediation of mold in buildings, the contents of buildings; disinfecting plants and foodstuffs, including meats, vegetables, and fruits; disinfection of surfaces from vegetative bacteria, molds, fungi and their spores, especially for remediation in non-line-of-slight applications; and liquid disinfectants of equipment such as tanks, passenger cars, all military vehicles, aircraft, and related equipment.